More than 100 million lithium batteries have been packed incorrectly in airline passengers’ checked luggage, prompting a new safety campaign warning the devices could pose a potentially deadly fire risk if transported improperly.

The campaign, launched by the UK Civil Aviation Authority (CAA) on June 26, comes as regulators warn that incorrectly packed rechargeable lithium batteries can trigger thermal runaway, creating fires that may be impossible to contain in an aircraft’s cargo hold.

The CAA’s ‘Pack Right. Safe Flight.’ campaign urges passengers to carry rechargeable lithium batteries — including power banks, mobile phones, laptops and vapes — in their cabin baggage rather than checked luggage. Travellers are also advised not to charge power banks during flights and to ensure laptops are completely switched off if placed in checked baggage.

According to the regulator, incidents involving overheating or malfunctioning lithium battery-powered devices are occurring at an average rate of around two per week. Reports of overheating or malfunctioning passenger devices nearly doubled between 2024 and 2025, while incidents involving incorrectly packed lithium battery devices increased by 91% over the same period.

The CAA estimates the average airline passenger now travels with four lithium battery-powered devices, meaning a fully loaded Airbus A380 could be carrying more than 2,000 such devices on a single flight. However, research commissioned by the regulator found that 36% of passengers remain unaware that rechargeable lithium batteries should not be packed in checked luggage.

The concern extends beyond the UK. In the US, the Federal Aviation Administration (FAA) recorded 95 verified lithium battery incidents involving smoke, fire or extreme heat on aircraft during 2025. The FAA says thermal runaway can occur if a battery is damaged, overheated, exposed to water, overcharged or improperly packed, although manufacturing defects can also trigger the process.

Giancarlo Buono, the CAA’s group director of safety and airspace regulation, said: “Flying is by far the safest way to travel, and we want to keep it that way. Pack right for a safe flight, and that means don’t put your batteries in your checked bag. Take them into the cabin with you.”

The campaign highlights the growing focus on lithium battery safety across the aviation sector as increasing numbers of passengers travel with battery-powered electronic devices and portable energy storage products.